In-situ oxidized films for use as gap layers for a spin-valve sensor and methods of manufacture

ABSTRACT

Disclosed is a spin-valve sensor disposed between first and second gap layers and formed of one or more in-situ oxidized films. The improved spin valve sensor helps eliminate electrical shorting between the spin-valve sensor and shield layers. A fabrication method of the gap layers comprises repeatedly depositing a metallic films on a wafer in a DC-magnetron sputtering module of a sputtering system, and then transferring the wafer in a vacuum to an oxidation module where in-situ oxidation is conducted. This deposition/in-situ oxidation process is repeated until a designed thicknesses of gap layers is attained. Smaller, more sensitive spin-valve sensors may be sandwiched between thinner gap layers formed of in-situ oxidized films, thus allowing for greater recording data densities in disk drive systems.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part of our co-pendingpatent application Ser. No. 09/919280, filed on Jul. 31, 2001 forIn-Situ Oxidized Films for Use as Cap and Gap Layers in a Spin-ValveSensor and Methods of Manufacture.

BACKGROUND OF THE INVENTION

[0002] 1. The Field of the Invention

[0003] The present invention relates to spin-valve sensors for readinginformation signals from a magnetic medium and more particularly tonovel structures for spin-valve sensors and magnetic recording systemswhich incorporate such sensors.

[0004] 2. The Relevant Art

[0005] Computer systems generally utilize auxiliary memory storagedevices having magnetic media on which data can be written and fromwhich data can be read for later use. A direct access storage device,such as a disk drive incorporating rotating magnetic disks, is commonlyused for storing data in magnetic form on the disk surfaces. Data arerecorded on concentric, radially spaced tracks on the disk surfaces.Magnetic recording heads carrying read sensors are then used to readdata from the tracks on the disk surfaces.

[0006] In high capacity disk drives, a giant magnetoresistance (GMR)head carrying a spin-valve sensor is now extensively used to read datafrom the tracks on the disk surfaces. This spin-valve sensor typicallycomprises two ferromagnetic films separated by an electricallyconducting nonmagnetic film. The resistance of this spin-valve sensorvaries as a function of the spin-dependent transmission of conductionelectrons between the two ferromagnetic films and the accompanyingspin-dependent scattering which takes place at interfaces of theferromagnetic and nonmagnetic films.

[0007] In the spin-valve sensor, one of the ferromagnetic films,referred to as a pinned layer, typically has its magnetization pinned byexchange coupling with an antiferromagnetic film, referred to as apinning layer.

[0008] The magnetization of the other ferromagnetic film, referred to asa “sensing” or “free” layer is not fixed, however, and is free to rotatein response to the field from the magnetic medium (the signal field). Inthe spin-valve sensor, the GMR effect varies as the cosine of the anglebetween the magnetization of the pinned layer and the magnetization ofthe sensing layer. Recorded data can be read from a magnetic mediumbecause the external magnetic field from the magnetic medium causes achange in the direction of magnetization in the sensing layer, which inturn causes a change in the resistance of the spin-valve sensor and acorresponding change in the sensed voltage.

[0009]FIG. 1 shows a typical prior art GMR head 100 comprising a pair ofend regions 103 and 105 separated by a central region 102. The centralregion 102 is formed by depositing a spin-valve sensor 128 onto a bottomgap layer 118, which is previously deposited on a bottom shield layer120, which is, in turn, previously deposited on a substrate. Two endregions 103 and 105 abut the edges of the central region 102. In thespin-valve sensor 128, a ferromagnetic sensing layer 106 is separatedfrom a ferromagnetic pinned layer 108 by an electrically conductingnonmagnetic spacer layer 110. The magnetization of the pinned layer 108is fixed through exchange coupling with an antiferromagnetic pinninglayer 114. This spin-valve sensor includes seed layers 116, on which thepinning, pinned, spacer and sensing layers of the spin-valve sensor 128grow with preferred crystalline textures during sputtering so thatdesired improved GMR properties are attained. The end regions 103 and105 are also formed by depositing longitudinal bias (LB) and conductinglead layers 126 on the bottom gap layer 118 and at the spin-valve sensor128. The end regions 103, 105 abut the central region 102. The centraland end regions are sandwiched between electrically insulatingnonmagnetic films, one referred as a bottom gap layer 118 and the otherreferred as a top gap layer 124.

[0010] The disk drive industry has been engaged in an ongoing effort toincrease the recording density of the hard disk drive, andcorrespondingly to increase the overall signal sensitivity to permit theGMR head of the hard disk drive to read smaller changes in magneticfluxes. The major property relevant to the signal sensitivity of aspin-valve sensor in the GMR head is its GMR coefficient. A higher GMRcoefficient leads to higher signal sensitivity and enables the storageof more bits of information on a disk surface of a given size. The GMRcoefficient of the spin-valve sensor is expressed as ΔR_(G)/R_(//),where R_(//) is a resistance measured when the magnetizations of thefree and pinned layers are parallel to each other, and ΔR_(G) is themaximum giant magnetoresistance (GMR) measured when the magnetizationsof the free and pinned layers are antiparallel to each other.

[0011] In certain spin-valve sensors, particularly those withCo—Fe/Ni—Fe films as sensing layers 106, a cap layer 112 is often formedover the sensing layers. The cap layer 112 serves several purposes, andplays a crucial role in attaining a high GMR coefficient. For instance,a Cu cap layers is thought to induce spin filtering, while a Cu—O caplayer is thought to induce specular scattering. Both spin filtering andspecular scattering are believed to increase the GMR coefficient of aspin-valve sensor. In addition, a cap layer may be employed to preventthe underlying sensing layers from interface mixing occurringimmediately during depositions and oxygen diffusion occurring duringsubsequent annealing, thereby maintaining suitably soft magneticproperties of the sensing layer and improving the thermal stability ofthe spin-valve sensor. The term “soft magnetic property” refers to thecapability of a spin-valve sensor to sense very small magnetic fields.

[0012] Currently, a Ta cap layer is used in many conventional spin-valvesensors. However, the Ta cap layer does not exhibit desired specularscattering, and is considered inadequate in preventing the sensinglayers from interface mixing and oxygen diffusion. Interface mixingoriginates from direct contact between the sensing layers and the Ta caplayer, and causes a substantial loss in the magnetic moment of thesensing layers. For one currently used spin-valve sensor with 0.32memu/cm² sensing layers, this magnetic moment loss accounts for 25% ofthe magnetic moment of the sensing layers. Oxygen diffusion originatesfrom low passivity of the Ta cap layer, which oxidizes continuously andentirely during annealing, such that oxygen eventually penetrates intothe sensing layers, causing more losses in the magnetic moment of thesensing layers.

[0013] Another limiting factor of the disk drive recording density isthe dimensions of the GMR head. The recording density of the disk driveis inversely proportional to the total thickness of the spin-valvesensor, the gap layers 118 and 124. In other words, in order to increasethe disk drive recording density the thicknesses of the spin-valvesensor, the gap layers 118 and 124 must be decreased. Several challengeshave arisen in the miniaturization of the gap layers 118 and 124.

[0014] The primary duties of the gap layers 118 and 124 are to preventelectrical shorting between the spin-valve sensor 128 and the shieldlayers 120 and 130, and thus to ensure the functionality of thespin-valve sensor 128. In order to prevent this electrical shorting, aspin-valve sensor must be sandwiched between gap layers 118 and 124 ofsubstantial thicknesses. The gap layers 118 and 124 have been a limitingfactor in the miniaturization o f the GMR head 100, because as thethicknesses of the gap layers 118 and 124 decreases, the possibility ofelectrical shorting increases, causing the GMR head to benon-functional.

[0015] Thus, it can be seen from the above discussion that there is aneed existing in the art for an improved spin-valve sensor with anincreased GMR coefficient, and for improved gap layers with decreasedthicknesses.

OBJECTS AND BRIEF SUMMARY OF THE INVENTION

[0016] The apparatus of the present invention has been developed inresponse to the present state of the art, and in particular, in responseto the problems and needs in the art that have not yet been fully solvedby currently available GMR heads. Accordingly, it is an overall objectof the present invention to provide an improved GMR head that overcomesmany or all of the above-discussed shortcomings in the art.

[0017] To achieve the foregoing object, and in accordance with theinvention as embodied and broadly described herein in the preferredembodiments, an improved GMR head comprises an improved spin-valvesensor and improved top and bottom gap layers formed using adeposition/in-situ oxidation process of the present invention. A methodof the present invention is also presented for forming a gap layer froma plurality of in-situ oxidized metallic films using thedeposition/in-situ oxidation process.

[0018] In one embodiment, the top and bottom gap layers preferablyformed of multilayer in-situ oxidized Al films are formed on a wafer.The deposition/in-situ oxidation process is repeated until selectedthicknesses of the top and bottom gap layers are attained. Full in-situoxidization of the top and bottom gap layers is preferred for attaininghigh breakdown voltages.

[0019] The improved GMR head of the present invention is preferablyincorporated within a disk drive system configured substantially in themanner described above. In addition, the spin-valve sensor of theimproved GMR head of the present invention may comprise a cap layerformed of an in-situ oxidized metal film. In one embodiment, the film isAl, Hf, Si, Y, or Zr. In alternate embodiments of the invention, a noblemetallic film, e.g., Au, Cu, Rh, or Ru may be sandwiched between asensing layer and an in-situ oxidized cap layer.

[0020] In one embodiment, a bottom shield layer preferably formed of aNi—Fe film and a bottom gap layer preferably formed of an Al₂O₃ film aredeposited on a wafer. Multiple seed layers preferably formed of Al₂O₃,Ni—Cr—Fe and Ni—Fe films are deposited on the bottom gap layer. Apinning layer preferably formed of a Pt—Mn film is then deposited on themultiple seed layers. Pinned layers preferably formed of Co—Fe, Ru andCo—Fe films are then deposited on the pinning layer. A spacer layerpreferably formed of an oxygen-doped, in-situ oxidized Cu—O film is thendeposited on the pinned layer. Sensing layers preferably formed of Co—Feand Ni—Fe films are then deposited on the spacer layer. A cap layerpreferably formed of an in-situ oxidized Al film (Al—O) is then formedon the sensing layer with a deposition/in-situ oxidization process.In-situ oxidization is preferred for attaining a high GMR coefficient.

[0021] The deposition/in-situ oxidation process preferably comprisesdepositing a metallic film in a vacuum in a DC magnetron sputteringmodule, and then conducting the in-situ oxidization for a wide range oftime in a wide range of oxygen pressures in an oxidation module. In oneembodiment given by way of example, the in-situ oxidization is conductedfor a period of about 8 minutes in an oxygen gas of about 0.5 Torr. Inanother embodiment given by way of example, the in-situ oxidization isconducted for a period of about 4 minutes in an oxygen gas of about 2Torr. The exposure to oxygen is preferably conducted with a moderatetemperature, such as ambient room temperature.

[0022] The top and bottom gap layers are preferably deposited using thedeposition/in-situ oxidization process of the present invention. Inorder to achieve designed thicknesses, multiple layers may bealternatively deposited and in-situ oxidized using thedeposition/in-situ oxidation process. Preferably, when forming the topand bottom gap layers, the alternating oxidized layers are fullyoxidized.

[0023] These and other objects, features, and advantages of the presentinvention will become more fully apparent from the following descriptionand appended claims, or may be learned by the practice of the inventionas set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order that the manner in which the advantages and objects ofthe invention are obtained will be readily understood, a more particulardescription of the invention briefly described above will be rendered byreference to specific embodiments thereof which are illustrated in theappended drawings. Understanding that these drawings depict only typicalembodiments of the invention and are not therefore to be considered tobe limiting of its scope, the invention will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

[0025]FIG. 1 is a cross-sectional view illustrating the structure of aGMR head of the prior art;

[0026]FIG. 2 is a schematic block diagram illustrating a magneticrecording disk drive system;

[0027]FIG. 3 is a cross-sectional view illustrating the structure of aGMR head in accordance with one embodiment of the present invention;

[0028]FIG. 4 is a schematic block diagram illustrating the structure ofa cap layer in one embodiment of the present invention;

[0029]FIG. 5 is a schematic block diagram illustrating a plurality ofin-situ oxidized Al films in an alternative embodiment of the presentinvention;

[0030]FIG. 6 is a schematic block diagram illustrating an integrated DCmagnetron/ion beam sputtering system suitable for use with the presentinvention;

[0031]FIG. 7 is a schematic flow chart illustrating a method fordeposition/in-situ oxidization of the present invention;

[0032]FIG. 8 is a cross-sectional view illustrating the structure of TMRhead in accordance with one embodiment of the present invention; and

[0033]FIG. 9 is a chart showing the sheet resistance (R_(s)) versus thein-situ oxidization time (t) for Al₂O₃/Ni—Fe and Al₂O₃/Ni—Fe/Al films.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034]FIG. 2 schematically depicts one example of a disk drive 200suitable for incorporating a GMR head of the present invention. As shownin FIG. 2, the disk drive 200 comprises at least one rotatable magneticdisk 212 supported on a spindle 214 and rotated by a disk drive motor218. The magnetic recording media on each magnetic disk 212 is in theform of concentric, annular data tracks (not shown).

[0035] At least one slider 213 is positioned on the magnetic disk 212.Each slider 213 supports one or more magnetic read/write heads 221incorporating the GMR head of the present invention. As the magneticdisk 212 rotates, the slider 213 moves back and forth across the disksurface 222, so that the read/write heads 221 may access differentportions of the magnetic disk 212 where desired data are recorded. Eachslider 213 is attached to an actuator arm 219 by means of a suspension215. The suspension 215 provides a slight spring force which biases theslider 213 against the magnetic disk surface 222. Each actuator arm 219is attached to an actuator 227.

[0036] The actuator 227 as shown in FIG. 2 may be a voice coil motor(VCM). The VCM comprises a coil movable within a fixed magnetic field,and the direction and speed of the coil movements are controlled by themotor current signals supplied by a controller 229.

[0037] During operation of the disk storage system, the rotation of themagnetic disk 212 generates an air bearing between the slider 213 andthe disk surface 222 which exerts an upward force or lift on the slider213. The air bearing thus counter-balances the slight spring force ofthe suspension 215 and supports the slider 213 off and slightly abovethe disk surface by a small, substantially constant spacing duringnormal operation. The surface of the slider 213, which includes the head221 and faces the surface of disk 212, is referred to as an air bearingsurface (ABS).

[0038] The various components of the disk storage system are controlledin operation by control signals generated by the control unit 229. Thecontrol signals include access control signals and internal clocksignals. Typically, the control unit 229 comprises logic controlcircuits, storage means, and a microprocessor. The control unit 229generates control signals to control various system operations such asdrive motor control signals on a line 223 and head position and seekcontrol signals on a line 228. The control signals on the line 228provide the desired current profiles to optimally move and position theslider 213 to the desired data track on the magnetic disk 212. Read andwrite signals are communicated to and from the read/write heads 221 bymeans of a recording channel 225. In the depicted embodiment, theread/write heads 221 incorporate a spin-valve sensor of the presentinvention.

[0039] Referring now to FIG. 3, shown therein is one embodiment of a GMRhead 300 employing the in-situ oxidized films of the present invention.While the GMR head 300 is discussed in relation to one example of a GMRsensor, the present invention is also applicable to other GMR sensors,the construction of which should be readily apparent from the presentdiscussion.

[0040] The depicted GMR head 300 includes a bottom-type syntheticspin-valve sensor, but of course, other types of spin-valve sensors mayalso be formed using the novel in-situ process of the present invention.The depicted GMR head 300 comprises a pair of end regions 303, 305separated by a central region 301. The central region 301 is formed bydepositing the spin-valve sensor 328 on a bottom gap layer 304. The endregions 303 and 305 are formed by depositing longitudinal bias (LB) andconducting lead layers 326 on a bottom gap layer 304. The end regions303, 305 abut the central region 301.

[0041] In accordance with one embodiment, ferromagnetic sensing layers307 (often collectively referred to as “free layers”) are shownseparated from ferromagnetic pinned layers 309 by a spacerlayer 316. Inone embodiment, the spacerlayer 316 is anon-magnetic 22 Å thick,electrically-conducting, oxygen-doped, in-situ oxidized Cu (Cu—O) film.Under one embodiment of the present invention, the sensing layers 307comprise a 9 Å thick Co—Fe film 318 and an adjacent 27 Å thick Ni—Fefilm 320. The pinned layer 309 comprises a 20 Å thick Co—Fe film 310, an8 Å thick Ru film 312, and a 22 Å thick Co—Fe film 314. Themagnetizations of the pinned layers 309 are fixed through exchangecoupling with a 200 Å thick antiferromagnetic Pt—Mn pinning layer 308.

[0042] One manner of forming the GMR head 300 of FIG. 3 will bediscussed herein by way of example. In the depicted embodiment, a bottomshield layer 311, preferably formed of a 1 μm thick Ni—Fe film, and abottom gap layer 304, preferably formed of a 100 Å thick Al₂O₃ film, aredeposited on a wafer 302. Seed layers 306 may then be deposited on thebottom gap layer 304.

[0043] In one embodiment, multiple seed layers 306, preferably formed ofa 30 Å thick Al₂O₃ film, a 30 Å thick Ni—Cr—Fe film, and a 10 Å thickNi—Fe film, are deposited on the bottom gap layer 304. The 100 Å thickAl₂O₃ film used as the bottom gap layer 304 may be sputter-deposited inan argon gas from an Al₂O₃ target, while the 30 Å thick Al₂O₃ film usedas the seed layer is preferably reactively sputter-deposited from an Altarget in mixed gases of argon and oxygen. The multiple seed layers areused to provide a desirable surface with a strong face-centered-cubic(FCC) {111} crystalline texture and coarse polycrystalline grains onwhich the remaining layers of the spin-valve sensor may be grownepitaxially in order to attain a high GMR coefficient.

[0044] An antiferromagnetic pinning layer 308, preferably formed of a200 Å thick Pt—Mn film, is then, under this embodiment, deposited on theseed layers 306. The pinned layers 309, preferably formed of a 20 Åthick Co—Fe film, an 8 Å thick Ru film, and a 22 Å thick Co—Fe film, arethen deposited on the pinning layer 308. A spacer layer 316, preferablyformed of an oxygen-doped, in-situ oxidized 22 Å thick Cu (Cu—O) film,is then deposited on the pinned layer 309. Sensing layers 307 are thenformed, preferably of a 9 Å thick Co—Fe film 318 and a 27 Å thick Ni—Fefilm 320, on the spacer layer 316. A cap layer 322, preferably formed ofan in-situ oxidized Al film (Al—O), is then formed on the sensing layers307. The cap layer 322 is preferably formed with the in-situdeposition/oxidization process of the present invention, one example ofwhich is discussed below with respect to FIG. 7.

[0045] The cap layer 322 may be formed of any suitable in-situ oxidizedfilm, examples of which include in-situ oxidized Al, Hf, Si, Y, and Zrfilms. An in-situ oxidized Al film is considered to be particularlyeffective, due to its amorphous state which is thought to promote highspecular scattering.

[0046] In addition, a metallic film may be disposed between the sensinglayer 307 and the cap layer 322. In one embodiment, the metallic filmcomprises a Cu film with a thickness in a range of between about 6 Å andabout 12 Å.

[0047] A top gap layer 324 is then preferably formed on the cap layer322. In one embodiment, the top gap layer 324 is a 100 Å thick Al₂O₃film. A top shield layer 325 may then be formed on top of the top gaplayer 324. In one embodiment, the top shield layer 325 is formed of a 1μm thick Ni—Fe film.

[0048] The low-passivity Ta film of the prior art cap layer (112 ofFIG. 1) oxidizes continuously and entirely. In contrast, using thedeposition/in-situ oxidation process of the present invention, ahigh-passivity film is oxidized only at its surface, resulting in anatural oxide cap layer which is dense and highly protective againstoxygen diffusion into the sensing layer.

[0049] The cap layer of the present invention is preferably onlypartially oxidized, with the upper portion of the film oxidized, whilethe lower portion of the film directly adjacent the sensing layerremains intact and substantially free from oxygen. The natural denseoxide layer formed in the upper portion of the film is thought toprovide higher specular scattering than a thick oxide film eithersputtered from an oxide target or reactively sputtered from a metallictarget in mixed gases of argon and oxygen. This high specular scatteringcauses a substantial increase in the GMR coefficient of the spin-valvesensor.

[0050] In addition, severe interface mixing between the sensing layerand a conventional Ta cap layer is substantially reduced, and oxygenpenetration from the conventional Ta layer into the sensing layer isprevented. As a result, the soft magnetic properties of the sensinglayers are substantially improved. In the preferred embodiments, thein-situ oxidized film is thick enough to ensure the metallic contactwith the sensing layer after the in-situ oxidization, but is also thinenough to avoid current shunting, which reduces the GMR coefficient.Hence, to form the in-situ oxidized cap layer in one example, an 8 Åthick Al film is deposited and in-situ oxidized for 8 min in an oxygengas of 0.5 Torr. After the in-situ oxidization, an approximately 10 Åthick in-situ oxidized Al (Al—O) film is formed. The in-situ oxidized Alfilm when used as a cap layer is preferably only partially oxidized, asdiscussed below with respect to FIG. 4.

[0051] To further reduce interface mixing and thereby further improvethe soft magnetic properties of the sensing layers, the metallic contactbetween the sensing and cap layers must be enforced. To enforce thismetallic contact, the deposition/in-situ oxidation process may also beapplied to noble metallic films with even higher passivity (e.g., Au,Cu, Rh, Ru, etc.) after the deposition of the sensing layers and beforethe deposition/in-situ oxidation processes applied to the Al film. Toform this additional in-situ oxidized cap layer, an 8 Å thick noblemetallic film is also deposited and in-situ oxidized for 8 min in anoxygen gas of 0.5 Torr. After the in-situ oxidization, an approximately10 Å thick in-situ oxidized noble metallic film is formed.

[0052]FIG. 4 illustrates one embodiment of an oxidized metallic film 400which may be formed with the deposition/in-situ oxidization process ofthe present invention. When used as a cap layer (e.g., 322 of FIG. 3),the thickness of the partially oxidized film 400 is preferably in arange of between about 5 and about 15 Å. The spin-valve sensor of theGMR head 300 may be sandwiched between the top and bottom gap layers 324and 304, which are formed of a plurality of in-situ oxidized layers,which will be explained in greater detail below with reference to FIG.5.

[0053]FIG. 5 illustrates an alternative embodiment in which repeateddeposition/in-situ oxidation processes are used to form the top andbottom gap layers 324 and 304. The top and bottom gap layers 324 and 304maybe formed of a plurality of in-situ oxidized metallic Al films 400.The deposition/in-situ oxidation process is repeated until designedthicknesses of the top and bottom gap layers 324 and 304 are attained.Each in-situ oxidized film 400 is formed in the manner described withrespect to FIG. 4. While reactive pulsed-DC magnetron sputter-depositionof an Al₂O₃ film is preferred for the first seed layer (which can alsobe treated as part of the bottom gap layer 304), full in-situ oxidationis preferred for the bottom gap layer 304 to ensure high breakdownvoltages.

[0054] While in-situ partial oxidation is preferred for the cap layer(which can also be treated as part of the top gap layer 324), fullin-situ oxidation is also preferred for the top gap layer 324 to alsoensure high breakdown voltages. Hence in one example, to form eachin-situ oxidized film as part of the top and bottom gap layer 324 and304, an Al film is deposited and in-situ oxidized for 16 min in anoxygen gas of 2 Torr. In another example, the Al film is oxidized for alonger time in the oxygen gas with a higher pressure. Thedeposition/in-situ oxidation process is repeated until the designedthickness is attained. In one example, each in-situ oxidized film has athickness of about 10 Å and 10 layers are deposited. In a furtherexample, up to 20 layers are deposited.

[0055] Referring now to FIG. 6, shown therein is one embodiment of anintegrated DC magnetron/ion beam sputtering system 600 suitable forfabricating the GMR head 300 and for conducting the deposition/in-situoxidation process of the present invention. The sputtering system 600 ofFIG. 6 is sold by the Veeco Corporation of Plainview, N.Y. Thesputtering system 600 as depicted comprises a transport module 602surrounded by a first single-target DC magnetron sputtering module 604,a multi-target DC magnetron sputtering module 606, a multi-target ionbeam sputtering module 608, and a second single-target DC magnetronsputtering module 610. Two loadlocks 616 allow the ingress and egress ofwafers. A control panel 614 controls the parameters and processes of thesputtering system 600.

[0056]FIG. 7 is a schematic flow chart illustrating one embodiment of amethod 700 of forming in-situ oxidized films of the present invention.The method 700 starts 702 and a metallic film is formed bysputter-deposition 704, preferably using an integrated DC-magnetron/ionbeam sputtering system, such as that described with reference to FIG. 6.Under the preferred embodiment of the present invention, thesputter-deposition 704 of the metallic film is accomplished in anatmosphere of argon gas of 3 mTorr.

[0057] Once the desired thickness of the metallic film on the wafer hasbeen achieved, the wafer is moved in a vacuum 706 through the transportmodule 602 to the single-target DC magnetron module 604 or 610, whichcan be used as an in-situ oxidization module. The metallic film 504 isthen in-situ oxidized in the oxidization module 604 or 610, where theoxygen gas is introduced 708. In one embodiment, the pressure of theoxygen gas in the oxidization module 604 or 610 is in a range of about0.5 to about 10 Torr. To ensure full in-situ oxidation, the pressure ofthe oxygen gas in the in-situ oxidation module 604 or 610 is preferably2 Torr or greater. The temperature is preferably maintained at aboutroom temperature (i.e., about 70 ° F.).

[0058] The full in-situ oxidation of the embodiment of FIG. 5 isconducted for a period of time of about 16 min in an oxygen gas of 2Torr. The in-situ oxidization is preferably a natural oxidizationperformed at ambient room temperature. When used to form multilayerfilms such as the embodiment of FIG. 5, the method 700 is repeated,until determining 710 that the selected number of layers or designedthickness has been reached. The method 700 then ends 712.

[0059] In one embodiment, the sputtering system 600 anddeposition/in-situ oxidation method 700 are used in the fabrication of aGMR head with cap and gap layers all formed of in-situ oxidized Alfilms. In this embodiment, the read gap thickness is designed to be assmall as 600 Å for magnetic recording at ultrahigh densities (≧30Gb/in²). To attain this read gap thickness, the spin-valve sensor of theGMR head is sandwiched between 100 Å thick Al—O top and bottom gaplayers.

[0060] The bottom gap layer 304 formed of 10 layers of in-situ oxidizedAl films are formed on a wafer in the first single-target DC magnetronsputtering module 604. The deposition/in-situ oxidation process isrepeated 10 times until a 100 Å thick bottom gap layer is attained. Toensure full in-situ oxidization that is preferred for attaining a highbreakdown voltage, the deposition of an Al film with DC magnetronsputtering from a pure Al target in an argon gas of 3 mTorr and thesubsequent in-situ oxidation for 16 minutes in an oxygen gas of 2 Torrare conducted alternatively for a total of 10 times.

[0061] After the formation of the bottom gap layer 304 in the firstsingle-target DC magnetron sputtering module 604, the wafer is thentransferred to the second single-target DC magnetron sputtering module610 for the deposition of the first seed layer that is in one embodimentformed of a 30 Å thick Al₂O₃ film. The Al₂O₃ film is deposited,preferably with reactive pulsed-DC magnetron sputtering from a pure Altarget in mixed argon and oxygen gases of 2.25 and 0.75 mTorr,respectively. This Al₂O₃ film when used as a seed layer in disclosedembodiments plays a significant role in increasing the {111} crystallinetextures of subsequently deposited films and in improving the GMRcoefficient of the spin-valve sensor. In contrast, an Al—O film, formedwith the deposition/in situ oxidation process, has been found to be anon-suitable seed layer.

[0062] The wafer is then transferred to the multi-target ion beamsputtering module 608 for the deposition of the second and third seedlayers that may be formed of a 30 Å thick Ni—Fe—Cr film and a 10 Å thickNi—Fe film, respectively. The Ni—Cr—Fe and Ni—Fe films are preferablydeposited in a xenon gas of 0.12 mTorr.

[0063] The wafer is then transferred to the multi-target DC magnetronsputtering module 606 for the deposition of the remaining layers of thespin-valve sensor, in one embodiment including a 200 Å thick Pt—Mn film,a 20 Å thick Co—Fe film, an 8 Å thick Ru film, a 22 Å thick Co—Fe film,an oxygen-doped/in-situ oxidized 22 Å thick Cu (Cu—O) film, a 9 Å thickCo—Fe film, a 27 Å thick Ni—Fe film, and a 10 Å thick in-situ oxidizedAl (Al—O) film. All the metallic films except the Cu—O film aredeposited in an argon gas of 3 mTorr and in a magnetic field of 40 Oeparallel to an alignment mark. To form the Cu—O film, a Cu film isdeposited in mixed argon and oxygen gases of 2.985 and 0.015 mTorr,respectively, and then in-situ oxidized in mixed argon and oxygen gasesof 2.94 and 0.06 mTorr for 4 minutes, respectively. To form the Al—Ofilm, an Al film is deposited in an argon gas of 3 mTorr and thenin-situ oxidized in an oxygen gas of 0.5 Torr for 8 minutes.

[0064] In addition, to form an additional Cu—O or Ru—O film before theformation of the Al—O film, a Cu or Ru film is deposited in an argon gasof 3 mTorr and then in-situ oxidized in an oxygen gas of 0.5 Torr for 8minutes.

[0065] After the depositions, the wafer is annealed for 300 minutes at265° C. in a magnetic field of 10 kOe perpendicular to an alignmentmark. After annealing, a 30 Å thick Ta film is deposited for the use asan adhesion layer for photoresist layers applied in the subsequentpatterning process. In this patterning process, bilayer photoresists areapplied and exposed in a photolithographic tool to mask the spin-valvesensor in a central region, and then developed in a solvent to form anundercut. The spin-valve sensor in unmasked end regions is removed byion milling until the Al₂O₃ first seed layer is exposed, andlongitudinal bias (LB) and first conducting leads (LD₁) layers areimmediately deposited.

[0066] Subsequently, the bilayer photoresists are lifted off and asimilar patterning process continues for the deposition of secondconducting leads (LD₂) layers. Ion milling or reactive ion etching isapplied to remove the 30 Å thick Ta film. The top gap layer-formed of 10layers of in-situ oxidized Al films is then formed on the wafer in thefirst single-target DC magnetron sputtering module 604. Thedeposition/in-situ oxidation process is repeated 10 times until about a100 Å thick top gap layer is attained. To ensure full in-situoxidization preferred for attaining high breakdown voltage, thedeposition of O) film, a 9 Å thick Co—Fe film, a 27 Å thick Ni—Fe film,and a 10 Å thick in-situ oxidized Al (Al—O) film. All the metallic filmsexcept the Cu—O film are deposited in an argon gas of 3 mTorr and in amagnetic field of 40 Oe parallel to an alignment mark. To form the Cu—Ofilm, a Cu film is deposited in mixed argon and oxygen gases of 2.985and 0.015 mTorr, respectively, and then in-situ oxidized in mixed argonand oxygen gases of 2.94 and 0.06 mTorr for 4 minutes, respectively. Toform the Al—O film, an Al film is deposited in an argon gas of 3 mTorrand then in-situ oxidized in an oxygen gas of 0.5 Torr for 8 minutes.

[0067] In addition, to form an additional Cu—O or Ru—O film before theformation of the Al—O film, a Cu or Ru film is deposited in an argon gasof 3 mTorr and then in-situ oxidized in an oxygen gas of 0.5 Torr for 8minutes.

[0068] After the depositions, the wafer is annealed for 300 minutes at265° C. in a magnetic field of 10 kOe perpendicular to an alignmentmark. After annealing, a 30 Å thick Ta film is deposited for the use asan adhesion layer for photoresist layers applied in the subsequentpatterning process. In this patterning process, bilayer photoresists areapplied and exposed in a photolithographic tool to mask the spin-valvesensor in a central region, and then developed in a solvent to form anundercut. The spin-valve sensor in unmasked end regions is removed byion milling until the Al₂O₃ first seed layer is exposed, andlongitudinal bias (LB) and first conducting leads (LD₁) layers areimmediately deposited.

[0069] Subsequently, the bilayer photoresists are lifted off and asimilar patterning process continues for the deposition of secondconducting leads (LD₂) layers. Ion milling or reactive ion etching isapplied to remove the 30 Å thick Ta film. The top gap layer-formed of 10layers of in-situ oxidized Al films is then formed on the wafer in thefirst single-target DC magnetron sputtering module 604. Thedeposition/in-situ oxidation process is repeated 10 times until about a100 Å thick top gap layer is attained. To ensure full in-situoxidization preferred for attaining high breakdown voltage, thedeposition of an Al film with DC magnetron sputtering from a pure Altarget in an argon gas of 3 mTorr and its in-situ oxidation in an oxygengas of 2 Torr for 16 minutes are conducted alternatively for 10 times.

[0070] The spin-valve sensors fabricated as described in this inventionhave been found to exhibit much better magnetic properties than aconventional spin-valve sensor with a Ta seed layer and a Ta cap layer.

[0071] Table 1 lists magnetic and magnetoresistive properties ofspin-valve sensors used in the prior art and in this invention. TABLE 1Seed Layer Ta Al₂O₃/Ni—Cr—Fe/Ni—Fe Al₂O₃/Ni—Cr—Fe/Ni—FeAl₂O₃/Ni—Cr—Fe/Ni—Fe Cap Layer Ta Al—O Cu—O/Al—O Ru—O/Al—O m₁ (memu/cm²)0.28 0.32 0.32 0.32 λ_(S) (×10⁻⁶) −0.3 +0.15 −1.2 −1.58 H_(C) (Oe) 14.36.2 6.2 6.2 H_(F) (Oe) −25.3 −6.6 −12.1 −12.5 R_(//) (Ω/ ) 20.2 16.615.6 16.4 ΔR_(G)/R_(//) (%) 7.7 13.8 13.4 13.4 ΔR_(G) (Ω/ ) 1.56 2.292.09 2.20

[0072] The replacement of the Ta cap layer with the in-situ oxidized caplayer causes an increase in the areal magnetic moment of the sensinglayer (m₁) from 0.28 to 0.32 memu/cm², a decrease in the amplitude ofthe ferromagnetic coupling field (|H_(F)|) from 25.3 to 6.6 Oe, and adecrease in the easy-axis coercivity (H_(C)) from 14.3 to 6.2 Oe. Thesechanges in magnetic properties may originate from substantially reducedinterface mixing at the interface between the sensing and in-situoxidized cap layers. The replacements of the Ta seed and Ta cap layerswith the Al₂O₃/Ni—Cr—Fe/Ni—Fe seed and Al—O cap layers, respectively,cause a decrease in the sheet resistance of the spin-valve sensor(R_(//)) from 20.2 to 16.6 Ω, but an increase in the GMR coefficient(ΔR_(G)/R_(//)) from 7.7 to 13.8%. These changes in magnetoresistiveproperties may originate from grain coarsening in the spin-valve sensordue to recrystalization in the Ni—Cr—Fe/Ni—Fe films, and improvedspecular scattering at the interface between the sensing and in-situoxidized cap layers.

[0073] In addition, the sandwiching of the Cu—O or Ru—O cap layerbetween the sensing and Al—O cap layers causes a slight decrease inΔR_(G)/R_(//), and a transition in the saturation magnetostriction ofthe sensing layer (λ_(S)) from positive to negative values. Thistransition may originate from an enforced metallic contact between thesensing and cap layers. This negative λ_(S) is preferred and istypically controlled in a range from −2×10⁻⁶ to −1×10⁻⁶ for improvingmagnetic and thermal stability of the spin-valve sensor. Hence, in spiteof the fact that the use of the Cu—O or Ru—O cap layer causes the slightdecrease in ΔR_(G)/R_(//), it may nevertheless be employed for improvingmagnetic and thermal stability of the spin-valve sensor.

[0074] The in-situ oxidation process of the present invention may alsobe applied to other types of read heads, one example of which includes,a tunneling magnetoresistance (TMR) head comprising amagnetic-tunnel-junction sensor. The TMR sensor is well known in the artand shares a similar structure to the GMR head, discussed by way ofexample herein. Nevertheless, the application of the in-situ formed gaplayers of the present invention is also applicable to the TMR sensor, aswill be discussed. While one example of a TMR head having a TMR sensorof the prior art will be discussed here, the present invention likewiseapplies to other TMR heads, the construction of which should be readilyapparent from the present discussion.

[0075] Referring to FIG. 8, shown therein is a TMR head 800 comprising aTMR sensor 828 and a longitudinal bias (LB) stack 830 in a centralregion 801. FIG. 8 shows the lower portion of the TMR sensor and aninsulating gap layer 826 in each of a pair of end regions 803. The TMRsensor 828, the longitudinal bias (LB) stack 830, and the gap layer 826are formed by a suitable method such as DC-magnetron or ion-beamsputter-deposition on a wafer 802.

[0076] In the TMR sensor 828, ferromagnetic sensing layers 807 areseparated from ferromagnetic transverse pinned layers 809 by a 6 Åthick, in-situ oxidized, Al (Al—O) barrier layer 812. Under oneembodiment of the present invention, the sensing layers 807 comprise a 9Å thick Co—Fe film 814 and an adjacent 27 Å thick Ni—Fe film 816. Thetransverse pinned layers 809 comprise an 18 Å thick Co—Fe film 806, an 8Å thick Ru film 808 and a 24 Å thick Co—Fe layer film 810. Themagnetizations of the transverse pinned layer 809 are fixed throughexchange coupling with a 200 Å thick antiferromagnetic Pt—Mn transversepinning layer 804 in a transverse directional perpendicular to an airbearing surface (ABS).

[0077] In the LB stack 830, a ferromagnetic 30 Å thick Co—Felongitudinal pinned layer 820 is separated from the ferromagneticCo—Fe/Ni—Fe sense layers 807 by a 30 Å thick nonmagnetic Ru decouplinglayer 818, and is overlaid with a 60 Å thick antiferromagnetic Ir—Mnlongitudinal pinning layer 822 and a nonmagnetic 90 Å thick Ru cap layer824. The magnetization of the longitudinal pinned layer 820 are fixedthrough exchange coupling with the antiferromagnetic Ir—Mn longitudinalpinning layer 804 in a longitudinal directional parallel to the ABS.

[0078] In one embodiment of a manner of forming the TMR head 800, abottom shield layer 802, preferably formed of a 1 μm thick Ni—Fe film,and a seed layer 811, preferably formed of a 90 Å thick Ta film aredeposited on a wafer 801. An antiferromagnetic pinning layer 804,preferably formed of a 200 Å thick Pt—Mn film is deposited on the seedlayers 811.

[0079] The pinned layers 809 are deposited on the pinning layer 804 anda barrier layer 812, preferably formed of an in-situ oxidized 6 Å thickAl (Al—O) film is deposited on the pinned layers 809. The sensing layers807 are deposited on the barrier layer 812.

[0080] The LB stack, preferably formed of a 30 Å thick Ru film, a 40 Åthick Co—Fe film, a 60 Å thick Ir—Mn film, a 90 Å thick Ru film, and a30 Å thick Ta film are then deposited on the sensing layer 807. All thedepositions are preferably conducted with DC magnetron sputtering.

[0081] The LB stack in the central region plays a crucial role inachieving sensor stability, attaining high signal sensitivity, attaininghigh read efficiency, and eliminating side reading. The sensor stabilitycan be easily achieved due to magnetostatic interactions betweenmagnetic moments of the sense and the longitudinal pinned layers, whichform a flux closure after the TMR sensor 828 overlaid with the LB stack830 is ion-milled for the definition of the sensor width. The highsignal sensitivity can be attained since the magnetic moment of thelongitudinal pinned layer is only needed to be 1.5 times of the magneticmoments of the sense layers for sensor stability, instead of more than 6times when Cr/Co—Pt—Cr films are used in the first embodiment. The highread efficiency can be attained since stray fields stemming from theCo—Pt—Cr film used in the first embodiment do not exist at sensor edges.As a result, stray-field induced sensor stiffness at sensor edges issubstantially reduced. Side reading can be eliminated since the TMRsensor and the LB stack are self-aligned in the fabrication process. Asa result, a precise read width control can be achieved.

[0082] After the depositions, the wafer is annealed for 300 minutes at265° C. in a magnetic field of 10 kOe perpendicular to an alignmentmark, and then annealed again for 20 minutes at 240° C. in a magneticfield of 200 Oe parallel to the alignment mark. These two anneals Afterthe depositions, the wafer is annealed for 300 min at 265° C. in amagnetic cause the Pt—Mn film to pin the magnetizations of theCo—Fe/Ru/Co—Fe films in a direction perpendicular to the alignment mark,and cause the Ir—Mn film to pin the magnetization of its underlyingCo—Fe film in a direction parallel to the alignment mark. After thesetwo anneals, bilayer photoresists are applied and exposed in aphotolithographic tool to mask the magnetic-tunnel-junction sensor TMRsensor 828 and the LB stack 830 in a read the central region, and thendeveloped in a solvent to form an undercut.

[0083] Unmasked TMR sensor 828 and the LB stack 830 in unmasked endregions 803, 805 of the GMR head 800 are removed by ion milling untilthe Al—O barrier layer is exposed. Subsequently, a gap region 826 isformed by depositing a plurality of layers, preferably formed of in-situoxidized Al (Al—O), on the exposed Al—O film. In one embodiment, 22layers are formed. The repeated deposition/in-situ oxidization processis preferably identical to that described above for FIG. 7. After thisrepeated deposition/in-situ oxidization process, the bilayer photoresistmask is lifted off, and a further patterning process is applied to thewafer for opening the central region. Ion milling or reactive ionetching is applied to remove the 30 Å thick Ta film and a top shieldlayer 825, preferably formed of a 1 μm thick Ni—Fe film, is deposited inthe central region.

[0084] It should be noted that a partial in-situ oxidation is preferredfor the formation of the cap layer of the spin-valve sensor, an optimalin-situ oxidation is preferred for the formation of the barrier layer ofthe magnetic-tunnel-junction sensor, and a full in-situ oxidation ispreferred for the formation of the gap layers of the GMR head 700 andthe TMR head 800. The partial in-situ oxidation may be attained afterdeposition of a 8 Å thick Al film and in-situ oxidation for 8 minutes inan oxygen gas of 0.5 Torr. The optimal in-situ oxidation may be attainedafter deposition of a 5.6 Å thick Al film and in-situ oxidation for 4minutes in an oxygen gas of 2 Torr. Likewise, the full in-situ oxidationmay be attained after deposition of a 8 Å thick Al film and in-situoxidation for 16 minutes in an oxygen gas of 2 Torr.

[0085] In conducting the in-situ oxidization operations of the aboveembodiments, the Al films are preferred to be as thin as possible. Athicker Al film may be used and may be exposed to air for full ex-situoxidization, but this full ex-situ oxidization is less preferred, as itmay cause air contamination.

[0086] To determine suitable oxygen pressures and in-situ oxidizationtime needed for the full in-situ oxidization, the in-situ oxidationprocess is preferably monitored by in-situ probing. In so doing,Al₂O₃(30)/Ni—Fe(20) and Al₂O₃(30)/Ni—Fe(20)/Al(10) films are depositedon a glass substrate in DC magnetron sputtering modules, and are in-situprobed either during staying in a vacuum of 4×10⁻⁸ Torr or duringin-situ oxidization in an oxygen gas of 2 Torr in an oxidation module,and then capped with a 60 Å thick Ta film.

[0087]FIG. 9 shows the sheet resistance (R_(s)) attained under thepresent invention versus the in-situ oxidization time (t). Initialprobing reveals that the Al₂O₃/Ni—Fe/Al films exhibit an R_(s) higherthan the Al₂O₃/Ni—Fe films. This probing result is somewhat surprising,since both the low electrical resistivity of the Al film (6.0 μΩ-cm),which is much lower than of the Ni—Fe film (23.5 μΩ-cm), and an increasein the total film thickness should theoretically only cause asubstantial decrease in R_(s). However, it is believed by the inventorsthat atomic mixing at the interface between the Ni—Fe and Al films mayoccur, and thus cause a more substantial increase in R_(s). Subsequentprobing in the vacuum of 4×10⁻⁸ Torr reveals continuing increases inR_(s) for both the Al₂O₃/Ni—Fe and Al₂O₃/Ni—Fe/Al films. In-situoxidization may thus gradually occur even in a vacuum where some oxygengases still exist.

[0088] The Al₂O₃/Ni—Fe/Al films are also preferably in-situ probed inthe vacuum of 4×10⁻⁸ Torr for the first 30 seconds, and then in anoxygen gas of 2 Torr. The R_(s) substantially increases to a maximumvalue as soon as the oxygen gas is introduced, and then begins todecrease. This probing result is also somewhat surprising, since oxygenpenetration during continuing in-situ oxidization should only cause anincrease in R_(s). It is believed by the inventors that this decrease inR_(s) indicates full in-situ oxidization, as described below. Afterintroducing the oxygen gas, the Al film becomes immediately oxidized,and when the Al atoms at the interface between the Ni—Fe and Al filmsinterface become oxidized, a sharp interface between the Ni—Fe and Al—Ofilms may be created. As a result, specular electron scattering mayoccur in the Ni—Fe film confined by the Al₂O₃ and Al—O films, leading tothe decrease in R_(s).

[0089] To determine suitable oxygen pressures and in-situ oxidizationtime needed for the full in-situ oxidization, in addition to the R_(s),the magnetic moment of the underlying Ni—Fe film may also be monitored.The Al₂O₃/Ni—Fe/Al—O/Ta films are preferably annealed for 300 minutes at265° C. in a direction parallel to the easy axis of the Ni—Fe film, andmagnetic properties of the Ni—Fe film are measured with ahigh-sensitivity vibrating sample magnetometer. If the desired fullin-situ oxidization is not attained yet, residual Al atoms in contactwith the Ni—Fe film may diffuse into the Ni—Fe film during annealing,causing a loss in the magnetic moment of the Ni—Fe film from 0.16memu/cm² (equivalent to 20 Å in Ni—Fe magnetic thickness) to 0.12memu/cm² (equivalent to 15 Å in Ni—Fe magnetic thickness). If thedesired full in-situ oxidization is attained, the Al—O film in contactwith the Ni—Fe film protects the Ni—Fe film from oxygen penetration,thus maintaining the entire magnetic moment of the Ni—Fe film at 0.16memu/cm² (equivalent to 20 Å in Ni—Fe magnetic thickness).

[0090] The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A spin-valve sensor disposed between gap layers,comprising: an antiferromagnetic pinning layer; a pinned layer disposedto one side of the antiferromagnetic pinning layer; a sensing layer; aspacer layer disposed between the pinned layer and the sensing layer;and a gap layer disposed to one side of the antiferromagnetic pinninglayer, the gap layer comprising a plurality of oxidized metallic films.2. The spin-valve sensor of claim 1, wherein the gap layer comprises afirst gap layer disposed to one side of the antiferromagnetic pinninglayer and further comprising a second gap layer disposed to one side ofthe sensing layer; the first and second gap layers comprising aplurality of oxidized metallic films.
 3. The spin-valve sensor of claim1, wherein the gap layer is formed of a plurality of in-situ oxidizedmetallic films:
 4. The spin-valve sensor of claim 2, wherein at leastone of the first gap layer and the second gap layer is formed of anin-situ oxidized metallic film.
 5. The spin-valve sensor of claim 2,wherein the first gap layer and the second gap layer are each formed ofa plurality of in-situ oxidized metallic films.
 6. The spin-valve sensorof claim 2, wherein the first gap layer and the second gap layer areeach formed of a plurality of in-situ oxidized Al metallic films.
 7. Thespin-valve sensor of claim 2, wherein the plurality of oxidizedmetallicfilms has a cumulative thickness in a range of between about 50 Å andabout 200 Å.
 8. The spin-valve sensor of claim 2, wherein the pluralityof oxidized metallic films has a cumulative thickness in a range ofbetween about 50 Å and about 200 Å.
 9. The spin-valve sensor of claim 2,wherein each of the plurality of films has a cumulative thickness ofabout 100 Å.
 10. The spin-valve sensor of claim 1, further a pluralityof seed layers disposed to one side of the antiferromagnetic pinninglayer; the seed layers comprising an Al₂O₃ film, a Ni—Cr—Fe film and aNi—Fe film; the antiferromagnetic pinning layer formed of a Pt—Mn film;the pinned layers formed of a Co—Fe film, Ru film, and a Co—Fe film; thespacer layer formed of an oxygen-doped, in-situ oxidized Cu film; thesensing layer formed of a Co—Fe film and a Ni—Fe film, and a cap layerformed of an in-situ oxidized metallic film.
 11. The spin-valve sensorof claim 10, further comprising a partially oxidized cap layer adjacentto the sensing layer.
 12. A disk drive system comprising: a magneticrecording disk; a spin-valve sensor for reading data recorded on themagnetic recording disk, the spin-valve sensor comprising: anantiferromagnetic pinning layer; pinned layers formed disposed to theantiferromagnetic pinning layer, the magnetizations of the pinned layerssubstantially fixed by the antiferromagnetic pinning layer; a sensinglayer formed of ferromagnetic films adjacent to the pinned layers, thesensing layers configured to have an electrical resistance that changesin response to changes in magnetic flux through the sensing layer; and acap layer disposed to one side of the sensing layers, the cap layerformed of a partially in-situ oxidized metallic film having a thicknessin a range of between about 5 and about 15 Å; a first gap layer disposedto one side of the antiferromagnetic pinning layer, the first gap layercomprising a plurality of oxidized metallic films; a second gap layerdisposed to the cap layer, the second gap layer comprising a pluralityof oxidized metallic films; an actuator for moving a read/write headcomprising the spin-valve sensor across the magnetic recording disk inorder for the spin-valve sensor to access different magneticallyrecorded data on the magnetic recording disk; and a detectorelectrically coupled to the spin-valve sensor and configured to detectchanges in resistance of the spin-valve sensor caused by rotation of themagnetization of the sensing layers relative to the fixed magnetizationsof the pinned layers in response to changing magnetic fields induced bythe magnetically recorded data.
 13. A method of fabricating a spin-valvesensor, the method comprising: forming an antiferromagnetic pinninglayer; forming pinned layers to one side of the antiferromagneticpinning layer; forming sensing layers; forming a spacer layer disposedbetween the pinned layers and the sensing layers; and forming a caplayer disposed to one side of the sensing layers by deposition andin-situ oxidation of a metallic film.
 14. The method of claim 13,further comprising forming first and second gap layers, the formingfirst and second gap layers comprising depositing a metallic film andin-situ oxidizing the metallic film.
 15. The method of claim 13, furthercomprising forming first and second gap layers, the forming first andsecond gap layers comprising forming a plurality of oxidized metallicfilms.
 16. The method of claim 15, wherein forming a plurality ofoxidized metallic films comprises forming a plurality of in-situoxidized aluminum films, each having a thickness in a range of betweenabout 5 and about 15 Å.
 17. The method of claim 13, wherein thedeposition and in-situ oxidation of the metallic film comprisesdepositing the metallic film in a vacuum in a deposition module andtransferring the metallic film to an oxidation module also in a vacuumand introducing an oxygen gas to the metallic film in the oxidationmodule in a controlled environment.
 18. The method of claim 17, whereindepositing a metallic film comprises depositing an Al film.
 19. Themethod of claim 17, wherein the deposition and in-situ oxidation of themetallic film comprises DC magnetron sputtering and in-situ oxidationfor a time in a range of between about 1 and about 100 minutes in anoxygen gas with a pressure in a range of between about 0.1 and about 10Torr.
 20. The method of claim 17, wherein introducing the oxygen gascomprises introducing the oxygen gas with a pressure in a range ofbetween about 0.5 and 5 Torr.
 21. The method of claim 17, whereinintroducing the oxygen gas comprises introducing the oxygen gas with apressure in a range of between about 1 Torr and about 3 Torr.
 22. Themethod of claim 17, wherein introducing the oxygen gas comprisesintroducing the oxygen gas with a pressure of about 2 Torr.
 23. Themethod of claim 17, wherein introducing the oxygen gas comprisesintroducing the oxygen gas for a period in a range of between about 4and about 12 minutes.
 24. The method of claim 17, wherein introducingthe oxygen gas comprises introducing the oxygen gas for a period in arange of between about 6 minutes and about 10 minutes.
 25. The method ofclaim 17, wherein introducing the oxygen gas comprises introducing theoxygen gas for a period of about 8 minutes.
 26. The method of claim 17,wherein introducing the oxygen gas is conducted at a temperature ofapproximately ambient room temperature.